Technical Abstract:
Neonatal calves are susceptible to disease, especially when exposed to stressful routine management practices. A good indicator of animal susceptibility or resistance to disease has not been found. In this experiment we measured three acute phase proteins, cortisol, and plasma IgG to determine if they are good indicators of stress in neonates and to establish normal neonatal concentrations of haptoglobin, alpha-1 acid glycoprotein and apolipoprotein-B. Eight calves were blocked by sex and date of birth. Blood was sampled by jugular venipuncture on d 1, 3, 7, 10, 14, 21, 28, 35 and 42. Heifer calves were sampled at d 48 and 56 after moving to group pens. Cortisol concentrations were similar to previous reports, with only non-significant increases observed with group penning. Haptoglobin was variable and frequently not detectable. Alpha-1 acid glycoprotein concentrations began high, 1077 micro/ml, and gradually fell to non-detectable concentrations. Neither dehorning nor group penning caused changes in alpha-1 acid glycoprotein. Apolipoprotein-B increased from d 1 to d 3 (385 to 515 micro/ml), then gradually fell to near d 1 concentrations by d 42. An increase (P<0.05) of apolipoprotein-B was detected at d 49 for heifers, corresponding to group penning. Apolipoprotein-B was the only indicator that we measured, reflecting stress associated with group penning. It may, therefore, be an indicator of a recent stressful event. However, it has not been correlated with the calf's tendency to resist or succumb to disease.